One eye of twelve chinchilla rabbits was treated with 150 spots of either SRT or conventional laser treatment. Right eyes of six rabbits received SRT(527nm, 20-25uJ, 200um) (SRT group; n = 6) and right eyes of the other six rabbits were treated with PRP( 577nm,150mW,200um) (PRP group; n = 6). Fluorescein angiography was performed to demonstrate SRT lesions(Figure1). The operated eyes were investigated with full-field ERG according to ISCEV standards at 1hr and at 3 weeks after treatment. The eyes were enucleated at 3 weeks after that, and hematoxylin and eosin staining was employed to monitor the extent and depth of the laser effects.

Results

At 1 day after treatment, ROD b-wave amplitude was reduced to 64 ± 4 % of baseline in the PRP group compared to baseline and 93 ± 6 % in the SRT group. This reduction was significantly larger in the PRP group than in the SRT group (P <0.05 ; t Test). Similar results were observed for the dark-adapted Combined Response (CR) b-wave amplitude, the reduction in CR b-wave amplitude was significantly larger in the PRP group than in the SRT group. CR a-wave, oscillatory potentials, cone single flash, and 30 Hz flicker responses showed no statistically differences in between-group analyses. At 3 weeks later, the differences were reduced due to recovery in both PRP and SRT groups. Especially b-wave amplitude in SRT group made no difference compared to baseline at 3 weeks. Histology showed selective RPE damage sparing photoreceptor continuity.

Conclusions

SRT in the rabbit eyes induces less functional loss than PRP group in both rod- and cone-mediated retinal function in full-field ERG. Especially SRT group showed no difference compared to baseline. These results suggest that SRT achieves selective targeting of the RPE without the inner and outer retinal damage.